At present, there are a growing number of fields for mixed reality headsets that allow a user to visualize holographic or augmented images that are combined with the real-world physical environment to create a mixed reality environment. These fields include, for example, scientific visualization, medicine and military training, engineering design and prototyping, tele-manipulation and tele-presence, and personal entertainment systems.
Unlike mixed reality systems, in virtual reality (“VR”) systems, VR headsets usually have opaque displays where computer-generated images, objects, or virtual scenes are displayed on the opaque displays while concurrently not allowing visualization of the outside real-world physical environment. Conversely, mixed reality systems (also known as augmented reality “AR” systems) usually have transparent displays that allow visualization of the outside real-world physical environment while concurrently displaying computer-generated holographic or augmented images. In other words, a mixed reality headset includes a transparent display that allows a user to see through the transparent display to the outside real-world physical environment while simultaneously seeing computer-generated holographic or augmented images on the transparent display, which are combined with the real-world physical environment to form a combined visual environment, in the field of view of the user. The combined visual environment includes both the real-world physical environment and the holographic or augmented images. In order to facilitate the illusion of three-dimensional depth, the displayed computer-generated images of the augmented objects are displayed independently to the left and right eyes of the user by the mixed reality headset (via independent displays for each eye) with a small binocular disparity between the augmented images. This binocular disparity is interpreted by the brain as indicative of a depth of the augmented object in the mixed reality environment.
Unfortunately, errors in the binocular disparity lead to problems with mixed reality headsets because small deviations in the in the position of the eyes of the user or binocular disparity can create a blurred image, discomfort, and loss of the three-dimensional effect. Specifically, deviations that cause horizontal errors in the position of the eyes of the user or binocular disparity generally result in errors of depth perception of the images. However, deviations that cause vertical error in the position of the eyes of the user or binocular disparity generally result in discomfort or headaches of the user because vertical misalignment between the eyes of the user result in overworking the brain of the user that is attempting to fuse the images together.
In order to minimize these effects, many mixed reality headsets are designed to have an interpupillary distance (“IPD”) that is as wide as possible for a given design of a mixed reality headset. The IPD is the distance between the centers of the pupils of the two eyes of the user and is important for the design of a binocular system (i.e., a viewing system that has separate eyepieces or displays for each eye of the user), where both eye pupils of the user need to be positioned within the exit pupils (e.g. eyepieces or displays) of the viewing system. Since different users typically have different IPDs, the different IPDs may result in binocular disparity or errors of the position of the eyes of the user with relation to the individual displays in the mixed reality headsets. As such, there in a need for varying the IPD of the mixed reality headset to accommodate users with different IPDs.
Known approaches to varying the IPD of mixed reality headsets have included software approaches that provide corrective display adjustments and some mechanical adjustment systems. However, software approaches generally do not perform as well as mechanical adjustment systems. Unfortunately, known mechanical adjustment systems are typically overly complex, bulky, and have limited range of motion. Therefore, there is a need for an improved mechanical adjustment system that overcomes these limitations.